The problem isn't technical feasibility but regulation. My city is one of the coldest (by lows, not average) capitals in Europe, and we have some of the stricte

The problem isn't technical feasibility but regulation. My city is one of the coldest (by lows, not average) capitals in Europe, and we have some of the strictest regulations in terms of energy requirements. New buildings have to be built with a total energy demand on par with Passivhaus standards, and renovated buildings (which includes adding an extension) have to be brought close to it. And of course, you cannot burn fossil fuels (which includes gas) for heating of newly built or renovated buildings. Yes this makes buildings a bit more expensive, and yes we are a poor country compared to Western Europe, but it works. If it can work here, there is no reason why it can't work anywhere else in Europe - the only reason why it hasn't been done elsewhere is because the politicians don't want to piss off their buddies in the construction sector. We have a lot of Soviet apartment blocks ("Khrushchyovka") which are basically just concrete and were built when gas was effectively free. These are being renovated up to modern standards as well, by wrapping them with external insulation. This of course changes the 'character' of the building, but I'm sure people said the same when wooden buildings were replaced with brick buildings.